High current rectifier



Jan. 21,-11947.

' c. ime KoTrERM/mV HIGH CURRENT RECTIFIER Filed arch 28, 1942 l Paten-teni elan lt? MGH CURRENT RECTIFIER application March 2s, i942, serial No. 436,711

l Claim.

1 il -This invention relates to new and useful improvements in mounting structures for rectifiers.

The objects of the invention are a rectifier assembly which requires few electrical contacts and which can be cooled easily.

With these objects in view, according to one feature of the invention, the electrode surfaces of a number of rectiers, e. g., selenium discs or plates, are pressed into contact with a metal supporting plate which functions as a' good heat radiator when placed in a cooling iiuid (oil, air, eta). This insures good heat conduction from the rectifier to the radiator and avoids the need of special contact lingers. A thin layer of a goed conductor, e. g., copper, may advantageously be provided between the rectifier and the plate.'

The exposed selenium edges oi the rectifier plates are, according to another feature of the invention, insulated from the metal plate by means of air spaces, coatings of varnish applied to the plates, or by thin insulating gaskets.

According to still another feature of the invention, the mounting plate is hollow to provide a large surface over which the cooling fluid may circulate.

These and other features of the invention will be explained in connection with Figs. l, 2 and 3 of the drawing which illustrates three embodiments, Figs. l and 2 in transverse cross-section and Fig. 3 in lengthwise cross-section, only so much being shown as is necessary for a clear understanding.

As shown in Fig. `l, a flat plate or disc l of metal coated with selenium and a counter-elec;-

trode is provided with two rings of insulating varnish t and d, one at the outer edge and the other around the customary central perforation in the plate. The varnish is applied to cover the exposed selenium, and overlaps the counter electrode ii sprayed on the selenium surface by about inch by any known means as masking devices or the like.

The varnish rings t and 3 are very thin (of the order ci a few thousandths of an inch) and sufficiently resilient so that when the rectifier I is pressed against a surface, e. g., a metal plate l, the electrode t will maire good contact over most of its area without the necessity of provlding special contact fingers or the like. The Varnish rings 2 and t prevent contact between the supporting plate t and the unsprayed seleniuin.

The means of bolts I0 passing through the perforations in the plates and corresponding perforarectifier plates are clamped in position by In Fig. 2 a structure is illustrated in which the rectifier discs I without varnish rings 2 and 3 are used. The metal plate 6 has raised platforms 1 provided on both faces by plating or spraying copper or other metal to a height lof approximately 0.02 inch. The platforms 'I are centered around the perforations in the supporting and their dimensions is such that when a rectifier plate I is placed thereon, the counter-electrode surface 5 overhangs the outer and inner edges of the platform by about of an inch as indicated at 0 and 9. Thus an insulating air space of approximately 0.02 inch separates the exposed selenium from the supporting plate 6. The rectifier plates I are held in position by the clamping means I0 passing through the perforations in the rectiiiers I and plate 6 and insulated from the latter as indicated at I I.

The metal plate 6 carrying any desired number of pairs of rectiers functions as a heat radiator and may be placed in an oil bath or in other suitable cooling fluid, e. g., a blast of air to cool the structure during operation.

Y The mounting plate may be hollow to serve as a better heat radiator. As shown in Fig. 3, two metal plates I2 and I3 are embossed so that when placed face to face they will enclose pairs of chambers I4, I5 separated by a restricted portion I6. The spacing within the restricted portion I6 is about En of an inch. The nextpair of chambere ld, l5 is spaced -from the previous pair by a restricted portion I1 which is longer than the 'restricted portion IE. Within the restricted portion I'I is placed a steel washer I8 and both the washer and the restricted portion I1 are perforated.

ln this structure the rectifier plates I are placed on the two faces of holes t in the plates registering with the holes through the restricted portions II.` The embossings serve the same purpose as the platforms 1 in Fig. 2, the outer and inner edges of plates i overhanging the depressions between adjacent embossings and being thus insulated from the metal supporting plate. Clamping bolts I9 insulated from the steel plates and the edges of the rectifier discs as indicated at 20 hold together the discs on the two sides ofthe plates.

In this as in the structures of Figs. 1 and 2. as many rectifier discs may be mounted on a complate y the hollow support with the sive of spring iinger contacts.

3 mon support as is required, and oil, air or other cooling uid may be caused to circulate between plates l2 and I3 and over the outside surfaces of the plates and the rectifier discs.

In none of the structures illustrated is it necessary to provide the customary spring finger contact to connect with the rectifier. In a 9 volt, 30,000 ampere, three-phase, full-wave bridge rectier, the standard stack construction of 112 mm.

4 ment capable of rectit g large' currents of electricity.

What is claimed is: In combination, two embossed metal plates enclosing chambers connected by restricted passages and forming on the outside embossings, washers between said plates in alternate restricted passages, the washers and the plates contacting therewith' being perforated, perforated rectier plates having electrodes contacting on both sides of the supporting assembly with the perforations in the plates and the rectifying members aligned, substantially the en ',ire surface of the electrode 'of each plate contacting with an embossing and the edge of the plate overhanging a depression between embossings, and clamping bolts projectingv through the perforations in the plates and the rectifying elements insulated from the plates and the edges of the rectiiiers. f

CHESTER A. KO'I'IERMAN. 

